The present invention relates to manually operable drain valves for liquid containers and in particular to a drain valve assembly for attachment to the threaded drain opening of an internal combustion engine crankcase.
According to conventional practice, oil is drained from an internal combustion crankcase by removing a drain plug and allowing the oil to discharge by gravity flow into a drain pan. This procedure is best carried out with the automobile carrying the internal combustion engine supported overhead on a hydraulic lift, or with the front wheels being disposed on ramps. The drain plug is a male threaded plug having an integral tightening head portion, with the diameter of the tightening head being larger than the plug portion and usually formed in a hexagon configuration for engagement by a wrench. Considerable torque must be applied to tighten or remove the usual drain plug. Anyone who has changed oil in an internal combustion engine will confirm that the drain plug removal procedure usually results in a large amount of oil being splashed onto the wrench, onto the operator's hands and sometimes onto the floor or ground. This situation can be extemely dangerous, especially if the oil is hot.
Moreover, the drain plug will be at the same temperature as the oil, and is thus difficult to handle by hand. The drain plug is small, and if dropped onto a hard surface, its threads can be damaged. It is likewise easy to drop the drain plug into the drain pan or onto the floor where it may roll away and become lost.
An additional problem in handling a conventional drain plug is the risk of cross-threading the plug or over-torquing the plug and stripping the drain hole threads as the plug is reinserted into the crankcase.
It is particularly difficult to remove the drain plug from the crankcase without the use of a hydraulic lift, or some other raising arrangement, since the clearance between the crankcase and the ground level is very small particularly on modern day automobiles. Moreover, in some engine arrangements, the drain plug is in a relatively inaccessible location, which limits the stroke range of back-and-forth manipulations of the wrench required for tightening or loosening the drain plug. It should be appreciated that the job of removing and reinserting the drain plug is complicated in such situations by the fact that the drain plug cannot be seen by the operator unless he is directly underneath it, and in some cases only with the aid of a light which will increase the danger of hot oil splashing upon the operator and burning him.
Known prior art relating to the subject matter of the instant application is shown in the following U.S. Pat. Nos.; 903,606 issued to J. C. Pollock; 3,477,459 issued to G. W. Schossow; 4,361,310 issued to J. W. Cummins and 4,907,672 issued to H. A. Shirdavani. These prior art patents are directed toward the similar problem, but are much more complicated than the quick drain drain plug of the instant application. Certain of these patents are directed to remotely controlled drain plugs; a drain plug that does not appear to have an arrangement to lock the plug in place other than through the compression between a valve seat and a cork closure member. While another patent is concerned with a very complicated arrangement having a double fastening arrangement to prevent the vibration of the automobile from opening up the drain plug. In each of these prior art arrangements, the valve seat is contained in the plug or part inserted into the crankcase with the valve closure member being provided by the moveable member which is caused to engage the valve seat in the member threaded into the crankcase.